Site Publish Fails at End

Sitecore 9.1

Publishes until all 190,000 items have been processed but fails at the end with the following:

Job started: Publish to 'web'|#Exception: System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation. ---> System.NullReferenceException: Object reference not set to an instance of an object.
at Sitecore.Data.ItemUri.Parse(String itemUri, ID& itemID, String& path, Language& language, Version& version, String& databaseName)
at Sitecore.Data.ItemUri.Parse(String itemUri)
at Sitecore.Data.Items.Item.GetItemUriFromSourceItem()
at Sitecore.Data.Items.Item.get_SourceUri()
at Sitecore.Data.Items.Item.get_Source()
at Sitecore.Data.Fields.Field.GetSourceItem()
at Sitecore.Data.Fields.Field.GetInheritedValue(Boolean allowStandardValue)
at Sitecore.Pipelines.GetFieldValue.GetInheritedValue.Process(GetFieldValueArgs args)
at (Object , Object )
at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
at Sitecore.Data.Fields.Field.GetValue(Boolean allowStandardValue, Boolean allowDefaultValue, Boolean allowFallbackValue, Boolean allowInheritValue, Boolean allowInnerValue)
at Sitecore.Data.Fields.Field.GetValue(Boolean allowStandardValue, Boolean allowDefaultValue, Boolean allowFallbackValue, Boolean allowInheritValue)
at Sitecore.Data.Fields.Field.GetValue(Boolean allowStandardValue, Boolean allowDefaultValue, Boolean allowFallbackValue)
at Sitecore.Data.Fields.Field.get_Value()
at Sitecore.Data.Items.ItemPublishing.GetBool(ID fieldId, Boolean defaultValue)
at Sitecore.Data.Items.ItemPublishing.IsPublishableInternal(DateTime date, Boolean checkAncestors)
at Sitecore.Data.Items.ItemPublishing.CacheDataRetrieving[T](String key, Func`1 getValueToCache)
at Sitecore.Data.Items.ItemPublishing.IsPublishable(DateTime date, Boolean checkAncestors)
at Sitecore.Publishing.PublishHelper.GetItemToPublish(ID itemId)
at Sitecore.Publishing.Pipelines.PublishItem.DetermineAction.Process(PublishItemContext context)
at (Object , Object )
at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
at Sitecore.Publishing.Pipelines.PublishItem.PublishItemPipeline.Run(PublishItemContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessPublishingCandidate(PublishingCandidate entry, PublishContext context, List`1& referrers, List`1& children)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessPublishingCandidate(PublishingCandidate entry, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessEntries(IEnumerable`1 entries, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessPublishingCandidate(PublishingCandidate entry, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessEntries(IEnumerable`1 entries, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessPublishingCandidate(PublishingCandidate entry, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessEntries(IEnumerable`1 entries, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessPublishingCandidate(PublishingCandidate entry, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessEntries(IEnumerable`1 entries, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessPublishingCandidate(PublishingCandidate entry, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.ProcessEntries(IEnumerable`1 entries, PublishContext context)
at Sitecore.Publishing.Pipelines.Publish.ProcessQueue.Process(PublishContext context)
at (Object , Object )
at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
at Sitecore.Publishing.Pipelines.Publish.PublishPipeline.Run(PublishContext context)
at Sitecore.Publishing.Publisher.PublishWithResult()
--- End of inner exception stack trace ---
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at Sitecore.Reflection.ReflectionUtil.InvokeMethod(MethodInfo method, Object[] parameters, Object obj)
at Sitecore.Jobs.JobRunner.RunMethod(JobArgs args)
at (Object , Object )
at Sitecore.Pipelines.CorePipeline.Run(PipelineArgs args)
at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain, Boolean failIfNotExists)
at Sitecore.Pipelines.DefaultCorePipelineManager.Run(String pipelineName, PipelineArgs args, String pipelineDomain)
at Sitecore.Jobs.Job.DoExecute()
at Sitecore.Jobs.Job.ThreadEntry(Object state)

Anyone else seeing this?  I have no idea where to start looking.

TIA